Tuesday, 24 May 2005 - 1:20 PM

This presentation is part of: Surface and Interface Science II

Water-Hydrophobic Interface at the Nanoscale: Wetting Study Indicates That Water is Separated From the Hydrophobic Walls by the Vapor Gap

Alexander Y. Fadeev, Seton Hall University, South Orange, NJ

We report an investigation of wetting of well-defined hydrophobic nanochannels prepared by silanization of mesoporous ordered silicas (SBA-15 type) with Rpore ~2-4 nm. Wetting in these systems can not be described by the classical models. Water occupies only fraction (30-60%) of the pore volume and the values of pressure for the pore filling are ~60-90% greater than predicted by the Laplace equation. The results are explained well using Derjaguin's model of wetting films and the concept of “disjoining pressure”. It is suggested that non-wetting fluid (water) is separated from the hydrophobic walls by thin film of the vapor phase (wetting fluid). The thickness of these films is estimated ~0.3-0.4 nm, or ~10-20% of the pore radius.

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